How can I get over my ex who cheated on me?

So I still like my ex. Me and my friends call all of our ex’s JJ. So then we don’t have to say the jerk’s names…. But anyways… So we broke up cause he cheated on me again for the 3rd time… With one of my friends… And that would be the 2nd time he did that with one of my friends… But the 1st time he did was with my “best friend”… That’s bad thing about it was in MY house in MY room…. When I wasn’t even that far away from him…. And her… (I would like to say him… To think he went gay or something but nope that didn’t happen…) I woke up and it was a mess… It was pretty bad… I guess they were writing notes saying they liked each other and they should make out… Well they did cause I found a hickey on the chick’s neck. I thought I was going to kill her but my dad didn’t know what the hell was going on so I didn’t even get to hurt her as much as I wanted to. But anyways.. I’m dating my ex’s cousin… And I probably shouldn’t be…. But the whole prob. is that I still like my Ex a lot and cant seem to get over him…. What should I do?

P.s He said he was ‘effed up!’ he smoked the joints. Big deal he is a flippin pot head… I think he knew what the hell he was doing.